Wave-guide resonator having various tuning ranges



W. SCHMIDT Sept. 24, 1968 WAVE-GU1DE RESONATOR HAVING VARIOUS TUNING RANGES 3 Sheets-Sheet 1 Filed Dec. 27, 1965 PRIOR ART T m mm mm W m T I G R A flA R A m. vm R L P 0 PRIOR ART w. SCHMIDT 3,403,360

WAVE-GUIDE RESONATOR HAVING VARIOUS TUNING RANGES Sept. 24,

3 Sheets-Sheet 2 Filed Dec. 27, 1965 INVENTOR.

WOLFGANG SCHMIDT ZGwe/e AGE Sept. 24, 1%8 w. SCHMIDT 3,403,360

WAVEGUIDE RESONATOR HAVING VARIOUS TUNING RANGES Filed Dec. 27, 1965 I 3 Sheets-Sheet 5 INVENTOR.

WOL FGANQ SCHMIDT BY 2% z. AGENT United States ABSTRACT OF THE DISCLOSURE In order to extend the tuning range of a tunable cavity resonator, for example for use in combination with a klystron, the cavity resonator is in the form of a rectangular waveguide having removable inner partitions parallel to the narrow waveguide walls, and the waveguide is formed in two sections which are joined together at the coupling apertures. Adjustable plungers are provided in each end of the waveguide between the partitions.

The invention relates to a wave-guide resonator having a rectangular cross-section for oscillating in the H101- resonance, and which can be tuned to various ranges.

HlOl-resonance is understood to mean the fundamental resonance of a rectangular resonator oscillating in the H-wave.

Since a wave-guide resonator oscillating in the fundamental resonance has the smallest number of possible modes of oscillation, its mechanical dimensions are the smallest possible; therefore, this type of resonator is preferably used in the decimeter and centimeter wave-technology.

Besides on the cross-section of the wave-guide the resonant frequency of a resonator of the above type also depends upon its length. With a given cross-section the resonator can be tuned, as is known, in a given range, for example, i20% of the average frequency, by means of a tuning plunger movable in the direction of the axis of the waveguide (z-axis). It is not possible to extend the tuning range considerably while maintaining the H101- mode of oscillation. If, however, a larger frequency range is to be covered, for example in the case of HF transmitters, the resonators, which in such devices are usually provided in great numbers, must be replaced by others. This is complicated and renders the manufacture and the storage cumbersome and expensive.

This is also true, for example, for transmitters, employing high-power klystrons. Generally, said klystrons are provided with a number of oscillatory circuits, for example, four resonators of the above type. The resonators are usually arranged on the outside on the annular electrode connections of the gaps of the klystron and are termed the cavities of the klystron.

It is the object of the invention to mitigate the above difliculties and to provide a resonator oscillating in the HlQl-resonance and having a rectangular wave guide cross-section, the resonator being tunable in a simple manner to a number of ranges.

According to the invention the resonator has at least one inserted partition wall, which reduces the wide side of the cross-section of the wave guide and by at least one exchangeable tuning plunger which is movable in the direction of the z-axis of the wave guide and is adapted to the resulting smaller cross-section of the wave guide. Preferably the partition (or partitions) is screwed in holes made for this purpose in the walls of the resonator and provided with spring contacts which are preferably .directed towards the outside of the resonator and make a atent O 3,403,360 Patented Sept. 24, 1968 ice ready, high-frequency contact with the resonator walls. The tuning plungers of such a resonator may be exchangeable and screwed to one or more adjusting shafts.

The invention may advantageously be used in a symmetrical resonator which, to permit arranging of the resonator on two preferably annular electrode connections of a discharge tube, in particular of the gap of a high-power klystron, can be divided in the central plane extending at right angles to the z-axis of the waveguide. Every wide wall in the centre line extending through said central plane is provided with apertures fitting with the electrode connections. A coupling member, for example, an inductive coupling member, preferably having a coaxial connection, is provided in the centre of one of the narrow walls. According to the invention two partition walls and two exchangeable tuning plungers are symmetrically ar ranged in the resonator, the partition wall adjacent the coupling member having a shape on the side facing the said coupling member so as to adjoin the coupling member in a disturbance-free manner. In a resonator having an inductive coupling loop and a coaxial connection it is favourable to connect the coupling loop to the inner conductor of the coaxial connection through an extension. The partition walls may each consist of two separable parts which are connected together electrically in the central plane in the resonator, for example, through spring contacts.

In order that the invention may readily be carried into effect, one embodiment thereof will now be described, in greater detail, by way of example, with reference to the accompanying drawing, in which- FIG. 1 is a plan-view and FIG. 2 is a side elevation of a known symmetrical klystron resonator which can be divided into two parts,

FIG. 3 is a perspective view of one of the halves of the resonator shown in FIGS. 1 and 2,

FIGS. 4 and 5 show a resonator which is tuned, by partition walls and exchangeable tuning plungers, to a higher frequency range which adjoins the frequency range of the known resonator,

FIG. 6 shows the way in which contacts are secured to the partition wall.

The resonator shown in FIGS. 1 to 3 comprises a metal wave guide 1 having a length 0 and a rectangular crosssection a.b the ends of which are terminated by walls 2 which are in a conductive contact with the said ends and the length c' of which in the direction of the z-axis of the wave guide which determines the resonant frequency can be varied by two symmetrically arranged tuning plungers. The tuning plungers are movable in the direction of the z-axis of the wave guide through mechanical means, for example, the adjusting shafts 4 shown diagrammatically in FIGS. 1 to 3, and are provided along the circumference with spring contacts 5 which make a satisfactory electric contact with the walls 6 and 7 of the wave guide. The adjusting shafts 4 are secured to the tuning plungers 3 by means of screw connections so that said connection can be detached again.

In the centre of the narrow wall 7 of the oscillator an annular flange 8 is provided to which (FIG. 3) a coupling member 9 with an inductive coupling loop 10 and a coaxial connection 11 is detachably secured.

In order to be able to arrange the resonator on two annular electrode connections of a discharge tube, for example, of the gap of a high-power klystron, the resonator is divided into two parts in the central plane 12 at right angles to the axis 2 of the wave-guides, said parts being secured together so as to be readily conducting, by mechanical means (not shown) for example, screws. In the centre line 13, extending through the central plane 12, apertures 14 are recessed which fit the electrode connections; when the resonator is connected a readily conducting electric connection between the resonator and the electrode connections is ensured, for example, by spring contacts (not shown) on the edges 15 of the aperture 14.

FIGS. 4 and 5 show in what manner the resonator as shown in FIGS. 1 to 3 is tuned to a high resonant frequency by each time two partition walls 16 and exchangeable tuning plungers 17 secured to the adjusting shaft 4 by screw connections. As a result of the partition wall 16 the dimension a in the direction of the x-axis of the wave guide is reduced to the dimension 0'; the dimension b in the direction of the y-axis remains unvaried so that the wave guide has obtained a cross-section a.b. The partition walls 16 each consist of two separable symmetrical parts which are electrically connected together in the central plane 12 of the resonator.

At the point of contact of the two halves 18 of the partition walls 16 the sides of the partition walls facing the coupling member are shaped into half cylinders in such manner as to adjoin the coupling member 9 in a disturbance free manner.

The coupling loop is arranged inside the resonator in a place suitable for the energy consumption by means of an extension 20 between the inner conductor 19 of the coaxial line 1.1 and the coupling loop 10.

FIG. 6 shows the way in which the long sides of the partition walls 16 are provided with spring contacts 21 which are directed outwards.

As a result of the partition walls 16 and the exchangeable tuning plungers 17, the resonance of the resonator is shifted to a higher average frequency, the relative tuning range of, for example, i20% being substantially maintained. With a set of partition walls and the associated tuning plungers a resonator is obtained which can be tuned in a simple manner to a number of successive tuning ranges so that one resonator can cover a larger range.

What is claimed is:

1. In an adjustable cavity resonator for use in combination with a discharge tube having a pair of spaced apart annular electrodes, said cavity resonator being comprised of a rectangular waveguide having a transverse aperture extending through each wide wall for connection to said pair of annular electrodes, and a coupling port extending through a narrow wall of said waveguide; the improvement wherein said waveguide is comprised of first and second waveguide sections in longitudinal alignment with adjacent ends of said sections being in contact at a junction, whereby said apertures and port extend through the waveguide walls at said junction, a pair of separate planar removable partitions fixedly positioned in each waveguide section, whereby the partitions in each said section are parallel to the narrow waveguide walls and are symmetrically positioned with respect to said narrow walls, and an adjustable plunger in each of said sections extending between the partitions therein, the ends of said partitions nearest the narrow wall through which said port extends having apertures in alignment with said port.

2. The cavity resonator of claim 1 in which a coaxial cable is connected externally to said port, comprising a coupling loop within said cavity between said partitions, and a removable extension connected between said loop and the center conductor of said cable.

References Cited UNITED STATES PATENTS 2,410,109 10/1944 schelleng 33383 2,694,795 11/1954 Pureka 333--83 2,854,532 9/1958 Robson 333-83 2,875,369 2/1959 Chambers 33383 FOREIGN PATENTS 892,681 3/1962. Great Britain.

HERMAN KARL SAALBACH, Primary EXUH'li/ILI'.

L. ALLAHUT, Assistant Examiner. 

